Alternating-current motor.



' w. A. LAYMAN.

ALTERNATING GURRENT MOTOR.- LLLLLLLLLLLLLLLLLLLL 29 1909.

952,532. Patented Mar. 22,1910.

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WITNESSES Wyn/T05 W-ALayman W QM W. A. LAYMAN. ALTERNATING CURRENT MOTOR.

APPLIOATION FILED JULY 29, 1909.

Patented Mar. 22, 1910.

2 SHEETS-SHEET a wAl aymah 5% W WALDO A.'LAYMA1\T, 0F WEBSTER GROVES, MISSOURI.

ALTERNATINGr-CURRENT MOTOR.

Specification of Letters Patent. Piitgnted D131. 22, 1910.

Application filed July 29, 1909. SeriaINo. 510,205.

To all whom it may concern:

Be it known that I, WALoo A. LAYMAN, a citizen of the United States, residing at the town of Webster Groves, in the county of St. Louis, State of Missouri, have invented a certain newand useful Alternating-Current Motor, of which the following is such a full, clear, and exact description as will enable any one skilled in the art to which it appertains to make and use the saline, reference being had to the accompanying drawings, forming part of this specification.

My invention relates to that type of alternate current motor which starts as a series induction. or repulsion machine and opcrates as a self-excited shunt induction motor bein converted from the former to the latter iorm of motor after a sufiic'ient speed has been reached.

My object is to improve the starting and runnin ossible, necessitating a very small. amount 0. manipulation on the part of the attendant, and to improve their power. factor.

Motorsof the said t e are known in which a commuted win ing is used on the induced member, generally the rotor, this winding being short-circuited at starting by means of brushes disposed along an axis not coinciding with that of the main in-- ducing or stator winding. Such machines start as series induction motors. ,When up to s eed a number of points of the rotor will; are short-circuited independently of the hrushes and the latter are sometimes lifted ofi'. One of the difilculties which arises with such motors is that the position of the short-circuited brushes which gives the-most desirable speed torque curve does not coincide with that position of these same brushes which secures the best commutation at starting. "Another dithculty is the somewhat low power factor of such a combination. ltovercome. these dificulties by 7 providing the rotor with an additional commuted winding connected to a commutator of its own. I make use of this commuted winding to increase the starting tor no and to improve the power factor, vi. a, e coinvpeiuuite the motor in normal operation.

performance of such machines, to .inake t .eir action as automatic as When making use of this auxiliary commuted winding to improve the starting torque I am able to place the short-circuited brushes on the other commutator in. such a position as to secure abetter commutation than would otherwise be possible'for the same starting torque.

In the: accompanying drawings Figure 1 is a' diagrammatic viewl' of. the preferred form of my improved motor; Fig. 2 shows how the compensating E. M. F. can be derived from an independent stator winding, and in this case the auxiliary commuted Winding is used only in normal operation;

shows another way of connecting the auxil- Fig. 3 is a modification of Fig. 1; Fig. i

iary commuted Winding at starting and also.

indicateshow theconipensating E. M. F-

can be derived from a transformer independent of the motor.

Referring to Fig. 1 which discloses the starting connections in one form of my improved. motor, the rotor carries two C0111 muted windings 7, 9 respectively connected to the commutators 8 and 10. The main stator inducing winding 3 is connected in series with the auxiliary commuted winding 7 by way of the brushes 5 and 6, the two windings being connected to the mains l and 2; The other rotor Winding 9 is connected to the commutator-l0 carrying two brushes 11, 12 short-circuited by conductor 13 and disposed along an axis not coinciding with that of the magnetization produced by the main stator winding 3. At the moment of starting the brushes 11,, 12 rest on the commutator 10 causing the machine to start as a self excited series induction motor. W hen a sufiicient speed has been reached then a number of: points of the commuted Winding 9 are short-circuited independently of the brushes 11, 12. This operation is performed bynieans of aster-shaped conductive body 2O capable of revolving about the motor shaft. For this purpose this body is moved in,the direction indicated by the curved arrow in'Fig. 1 and enga es with the points l4, l5, 16,17,1"8 and 19 ot 9, thus short-circuiting six oints of 9. The stator also carries an auxi iary winding i coaxially disposed with 'One end of dis directly connected to brush 5 at point 35 the other is connected loo to brush 6 by way of trolled switch nected to main 2 the centrifugaliy con- Brush 3 is not only conbut also to point ot the device are indicated at 29. l device geared to the motor shaft in any desired manner, for instance by means oi the pulley 36. When the motor has reached a su icient speed the movable switch contacts so, 27 complete the circuit between points 25 and 24 whereby a con pensating E. M. derived from iis impressed on the flUKlllfi. v commuted Winding. lhe fact that the au: nary commuted Winding '7 is connected in series with the i stator Wiiuling the ccntrit'uoal The centriiu o 22b .-l llC t e mam rotor Windingi -"uited along an. axis more or less dispnzccd with respect. to that of 3 causes the motor to start as a separately excited series induction motor. in this Way the auxiliary commuted Winding is made to contribute to the starting torque. T 1e brushes 5, 6 preferably displacc by about lFJO/n degrees with respect to the axis-of the main stator Winding, the letter n designating the number of poles of the mo tor. it is not necessary to lift brushes 11, 12 olt 10 When up to speed but I prefer to do so. Connection between points 25 and can of course be made by hand instead of by means o an automatic switch.

in Fig. 2 the Winding d from which the compensating E. M F. is derived is not. electrically connected to the stator inducing winding 8 but is nevertheless disposed. on the stator and preferably coasially with The compensating circuit is here supposed "to be closed hand. At starting switch 30 stands in on shown in big. When the a: .n'! c autizcien.

on points 38.

37, 38 and who connected to winding; 4.

In Fig. 5

sin l'tication of Fig. being taken winding; 4. in sei ihe main inc. icing Winding 3 in s nd of being" taken through the auxiliary in series with 3. hen

s been reached and it is c the motor then switch the operating Switch 31 desired. A

c u rrent.

a suliicieut s i'recd h desired to comp e closeo thu conditions oblau (an be clos-tcd number oi point. conmiuted Winding are also short uited speed has been reached by the same means illustrated inv .iiig. l.

in Fig. el the brushes 5 and 3 con-- nected to the secondary 323 of the tr:

32 is connected am 055 i'ormer 41, its primary utter a sufficient.

t i t t I i t I i i I J I i motor. When the motor. has reached a suihcicnt the commuted Winding 9 15 sh ort-ci rcu i d in some such. Way as indi.

coted Jig. and the short-circuitcd brushes can. be in: if desired.

Having fully ribed my invention, What I claim as new and desire to secure by Letters Patent of the United States, is

1. in an alternate current motor, the combinati on of a stator, a maininducing Windi 11g on the stator, rotor, a commuted Winding on the rotor short-circuited. by means of brushes, means for short-circuiting nuu1- ber of points of said coimnutcd Winding after a certain speed has been reached, a second commuted Winding on the rotor, and means for impressing a compensating F. M. F. onsaid second commuted winding.

2. in an alternate current motor. the combination of a stator, a main inducing Winding on the stator, a rotor, a commuted Winding on the rotor short-circuited by means of brushes alor an axis displaced from that of ti e main inducing Winding, means for short-cu'cuiting a number or points or said commuted Winding after a certain speed. has been reached. a commuted Winding on. the rotor, and means for impressinga compensating M. F. on said second commuted Winding.

3.- In an alternate current motor, the combination of a stator, a main inducing Winding on the stator, a rotor, a commuted Winding on the rotor short-circuited by means of brushes along an axis displaced from that. of the main inducing Winding, ms .ns tor short-circuiting a number of pen or said conunuied Winding after a certal. peed has been reached. a second commuted Winding on the rotor connected in series relation to' the main inducing winding and means for impressing a compensating E. M. F. on said second commuted Winding.

4. In an alternate current motor, the combination oi a stator, a main inducing Windin on the stator, a rotor, a commuted Windon the rotor short-circuited by means of us along an axis displaced from that the m ii'iducing Winding, means for icing number points of said commuted Winding after a certain speed has In testimony whereof I have hereunto set been reached, a second commuted Winding my hand and affixed my seal in the presence on the rotor connected in series relation to of the two subscribing Witnesses.

the main inducing Winding at starting, and .WALDO A. LAYMAN. [n 3.] 5 an auxiliary Winding on the stator for im- Witnessesz' pressing a compensating E. M. F, on said H. H SWINGLEY,

second commuted winding.

0. B. BENNETT. 

